A magnetic field is used in Magnetic Resonance (MR) Imaging to align the nuclear spins of atoms as part of the procedure for producing images within the body of a patient. This magnetic field is referred to as the B0 field. During an MR scan, Radio Frequency (RF) pulses generated by a transmitter or amplifier and an antenna cause perturbations to the local magnetic field and can be used to manipulate the orientation of the nuclear spins relative to the B0 field. Radio Frequency (RF) signals emitted by the nuclear spins are detected by a receiver coil, and these RF signals are used to construct the MRI images.
The B0 field for magnetic resonance imaging is typically generated using a superconducting magnet. The current flowing in the coils of the superconducting magnet may be changed or ramped up or down using an external power supply, load, or discharge system by connecting to current leads connected to the coils of the superconducting magnet.